GENETIC DIFFERENCES 

IN JUVENILE SHUMARD OAK 

This is a report on the genetic differences observed 

among seedlings of four seed collections of Shumard oak 

(~uercus shumardii var. shumardii) during the first 2 years 

of growth, It is based on data from replicated seedbed and 

nursery plots at the Michaux Quercetum. 

(The Michaux Quercetum is a cooperative project of the 

Northeastern Forest Experiment Station and the University of 

Pennsylvania's Morris Arboretum, at Philadelphia, Pa. The 

project was started in 1953 to provide an authenticated collection of native and exotic oak species for use in genetic 

and taxonomic studiesO1) 

Shumard oak, which commercially is a relatively unimportant species, was selected for this early report because 

of the outstanding nursery characteristics it displayed; no 

other species in the oak plantings exhibited such great differences in growth and fall leaf coloration, 

Significant differences in height growth were found 

among seed origins in 1954 at the end of the first growing 

season. But in 1955, after the second growing season, the 

differences were not significant. This change is attributed 

to dieback that occurredin the late fall and winter of 1954. 

A progressive increase in dieback was evident in origins 

from north to south, ranging from none in Illinois seedlings 

to 28 centimeters in those from Florida (table 1). 

The pattern of height growth exhibited by different 

loks of seedlings varied considerably during the first growing season. Measurements taken at three different periods 

in the season indicate that seedlings of northern origin 

grew more rapidly during the early part of the year; and by 

late in July they had nearly completed their annual height 

l~chranun, J. R., and Schreiner, Ernst J. The Michaux 

Quercetum. Univ. Pa. Morris Arboretum Bul. 5: 54-57, illus. 

1954. 
Table 1.--Data on seedlot origins and on seedling development by origins 

*Differences not significant at either the 1- or 5-percent level. 

*Differences significant at the 5-percent level. 

**Differences significant at the 1-percent level. 

Ited 

Table 2.--Autumn leaf coloration in four lots of Shumard oak seedlings, 

November i0-14 of their second year 

Latitude ............................ Degrees .. 38 36 33 30 

Seedlot number ................................ 420 215 284 332 

1954 progeny .................. No. seedlings .. 70 41 4 1 231 

*Germination period ..................... Days .. 8.0 7.0 6.8 8.8 

*Height growth, 1954 ............. Centimeters .. 25.3 28.7 45.1 48.8 

-Height In November 1955 ......... Centimeters .. 42.6 49.5 57.3 39.1 

'Dleback, 1954-55 ................ Centimeters .. 0.0 13.7 15.1 28.0 

**First-year growth ......... Percent of year's 

as of May 28-June 3 total growth .. 54 4 8 25 22 

'First-year growth ......... Percent of year's 

as of July 8-16 total growth .. 93 84 46 4 0 

'First-year growth ......... Percent of year's 

as of Aug. 16-27 total growth .. 98 97 72 75 

Orlgin (County and State) 

l/~rees that have leaves colored green in combination with other 

colors. 

County 

and State 

growth (table 1). This is in contrast to the southern seedlings, which grew slowly during the early part of the season 

but continued growth into the fall. 

Alachua Co. 

Fla. 

The lots of seedlings differed significantly from one 

another in total height growth, in amount of dieback, and in 

growth rate measured at three different time intervals during the 1954 growing season. The genetic variation within 

the species was further demonstrated by extreme variability 

in autumn leaf coloration (table 2). 

Tallahatchle 

Co . , Mlss. 

Richland Co. 

Ill. 

Percent Percent Percent 

Richland Co. 

Ill. 1 28 7 1 

Knox Co. 

Tenn. 7 6 6 27 

Tallahatchie 

Co. , Miss. 10 78 12 

Alachua Co. 

Fla. 77 15 8 

Grades of follage coloration 

The differences in autumn leaf coloration between 

origins are highly significant by Chi-square test. The delayed coloring in the trees of southern origins is in accord 

with their longer period of growth. That is, both the percentage of trees continuing growth late in the season, and 

the percentage still holding green leaves and presumably 

Knox Co. 

Tenn, 

All red, brown, or dropped leaves All green Intermediatel/ 
continuing photosynthesis in November, increased from northern to southern origins. 

The prolonged activity of foliage in southern trees 

was associated also with prolonged succulence of stems, 

which in turn resulted in an increasing amount of frost damage fram northern to southern origins. 

Because of the marked variations in juvenile growth 

and frost hardness, knowledge of seed origin seems essential 

for the efficient use of Shumard oak in tree breeding and 

planting programs. 

--WILLIAM J. GABRIEL, Geneticist 

Northeastern Forest Experiment Station 

Forest Service, U.S. Dept. Agriculture 

Mr. Gabriel, who is now at the Experiment Station's 

laboratory at Burlington, Vt., was stationed at the Morris 

Arboretum at the time of this study. He adds a note of 

thanks to the many individualswhohave made seed collections 

for the Michaux Querceutm, and to those who gave advice and 

made measurements in this study. 

AGR [CULTURE-FOREST SERVICE-UPPER DARRY